United States

Sterling and Crown Project

Click for more information

Categories

Overview

Mine TypeOpen Pit
StagePermitting
Commodities
  • Gold
Mining Method
  • Truck & Shovel / Loader
ShapshotAs a result of an acquisition, AngloGold Ashanti now controls a past-producing mine site in southern Nevada known as the Sterling mine, which has one applicable mining lease that expires in 2029, with the option to extend the lease for an additional ten-year period. Although the Sterling mine is currently in care and maintenance status, it remains subject to complex permitting and regulatory requirements, including compliance with relevant provisions of the U.S. Federal Mine Safety and Health Act of 1977 and oversight by the U.S. Department of Labor’s Mine Safety and Health Administration (“MSHA”).

The Sterling project includes the Crown Block deposits of SNA, Secret Pass and Daisy, and the tenements surrounding the properties.

Owners

SourceSource
CompanyInterestOwnership
AngloGold Ashanti plc. 100 % Indirect
The Sterling project is an indirect wholly owned and managed by AngloGold Ashanti.

Deposit type

  • Sediment-hosted
  • Carlin-type
  • Breccia pipe / Stockwork

Summary:

Geology The Sterling deposits are characterised as either epithermal deposits (Secret Pass) like the North Bullfrog and Silicon deposits or sediment-hosted deposits (Daisy, Sterling, and SNA). Oxidised gold appears to be controlled by thrust domains and steep north-striking faults in these deposits. Deposit type From oldest to youngest, stratified rock units on the Sterling property range from the Upper Proterozoic to the Ordovician part of the stratigraphic section. The host rocks of the 144 Zone mineralisation span the bottom of the Bonanza King Formation and the top of the Carrara Formation. Miocene quartz latite dykes of the SWNVF occur throughout the Sterling property, but most are along or close to the Reudy Fault zone. They normally range in thickness from 1.5m to about 9m, though some are considerably thicker. Most trend north-south and were probably intruded along faults or fractures. Clay-alteration of the dyke ranges from weak to locally intense. The dykes slightly pre-date the most important hydrothermal activity and gold mineralisation at Sterling. The Daisy deposits are located in the footwall of the Fluorspar Canyon fault where it intersects a prominent north-south fault system that connects with the Reward deposit to the south. Daisy is a sediment-hosted gold deposit. SNA can be described as a Carlin-type deposit hosted within Devonian carbonates in the footwall of the Fluorspar Canyon fault. Mineralisation style Sterling is typical of sediment-hosted, disseminated precious metal deposits. Gold occurs in the rims of microscopic arsenian pyrite grains. Significant mineralisation occurs in: - Gouge or breccia in the Reudy Fault zone and locally along the dyke margin. - Adjacent to the fault (on both sides) in Bonanza King silty dolostone or dolostone, and to a lesser degree in underlying Carrara silty limestone or limestone (proximity to the Reudy Fault is not requisite for mineralisation). - In hydrothermal breccias derived from the above lithologies. Mineralisation characteristics At Sterling, pyrite formed during hydrothermal alteration and brecciation resulting from the interaction between gold-bearing solutions rising along high-angle fault feeders from depth, soluble carbonate rocks, and the rheological contrast of ironbearing lithologies. Favourable geological conditions existed at the thrust contact and at the contact between the silty dolostone of the basal Bonanza King and the underlying Carrara limestone. Tertiary quartz dykes in the 144 Zone are also conducive for high-grade gold mineralisation.

Reserves

Lock

- subscription is required.

Mining Methods

Lock

- subscription is required.

Comminution

Crushers and Mills

Milling equipment has not been reported.

Processing

Lock

- subscription is required.

Production

CommodityUnits2015
All production numbers are expressed as metal in doré.

Production Costs

Commodity production costs have not been reported.

Heavy Mobile Equipment

Lock

- subscription is required.

Personnel

Mine Management

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Jul 17, 2023
....................... Subscription required ....................... Subscription required Subscription required Jul 17, 2023

EmployeesYear
...... Subscription required 2019
...... Subscription required 2018

Aerial view:

Lock

- subscription is required.